Find a Compatible Handset - Not all Bluetooth phones will work!
Unfortunately, not all Bluetooth compatible phones will work (partially or fully) with BMW's Bluetooth systems. As such, “Bluetooth” is an ambiguous term and insufficient to ensure compatibility. That is unfortunate, since "Bluetooth" is all that is typically included in the phone's description.

My experience is a good example: my do-everything SonyEricsson P900 does not work with my Bluetooth-capable car (the SonyEricsson P900 lacks a "handsfree profile" required to work with the BMW implementation of integration of cell phone and car). Successful 6 Series Bluetoth retrofit, but phone incompatible

Even if you have a "BT-compatible" phone with the BT "handsfree profile," there are other features that may or may not work properly. For example, the phone should automatically share its phone book with the car to enable a set of nice features: based on your phone's address book: Calling Name display and